Well surveying apparatus



- July 5, 1949. HENRI-GEORGES DOLL WELL SURVEYING APPARATUS OriginaIFiled June 13, 1942 SOURCE OF ELECTRICAL ENERGY) (RECORDER.

BY I W/ 2 Shets-Sheet 1 FIG. 2.

iNVENTOR.

HENRI-GEORGES DOLL 7 7% HIS ATTORNEYS.

July 5, 1949.

Original Filed June 13, 1942 SOURCE OF EL\EC'TR/CAL ENERGY 3( REfORDERHENRI- GEORGES DOLL WELL SURVEYING APPARATUS 2 Sheets-Sheet 2 INVENTOR.

HENRI-GEORGES oou.

HIS ATTORNEYS.

Patcnted July 5, 1949 WELL SURVEYING APPARATUS Henri-Georges Doll,Houston, Tex, assignor to Schlumberger Well Surveying Corporation,

Houston, Tex., a corporation of Delaware Original application June 13,1942, Serial No. 446,888. Divided and this application October 8, 1947,Serial No. 778,681

The present invention relates to apparatus for investigating earthformations traversed by a bore hole, and more particularly to new andimproved apparatus for determining the depth and thickness of permeableformations traversed by a bore hole.

This application is a division of my copending application Serial No.446,888, filed June 13, 1942, for Method and apparatus for investigatingearth formations traversed by a bore hole, now Patent No. 2,433,746,granted December 30, 1947.

The above-mentioned copending application discloses methods andapparatuses for investigating earth formations traversed by a bore holeby means of alternating electro-filtration potentials. The latterpotentials are created artificially by producing periodicallyfluctuating pressure in the bore hole liquid in the vicinity ofpermeable i'ormations, and they are picked up by electrodes connected tosuitable indicating means.

The present application is addressed specifically to one form ofapparatus in which mechanical means are employed for producing theperiodically fluctuating pressure in the bore hole liquid.

The invention may be better understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

Figure 1 is a schematic diagram in longitudinal.

section of apparatus constructed according to the invention forproducing alternating potentials related to electrofiltration potentialsin a bore hole;

Figure 2 illustrates a curve of spontaneous potentials such as might beobtained by means of the apparatus shown in Figure 1;

Figure 3 is a schematic" showing of a modified form of the invention;and

Figure 4 shows the type of electrofiltration potential curve producedwith the apparatus of Figure 3.

Referring now to Figure' l', the invention is shown embodied inapparatus'lll for producing periodic variations in the pressure of theliquid II at the level of a relatively permeable formation l3 traversedby a bore hole l2. It will be assumed in the following description thatthe pressure of the bore hole liquid l l is greater than the pressure ofany fluid contained in the formation l3, so'that electrofiltrationpotentials will be present. The apparatus It comprises preferably acylindrical water tight casing l4 containing an electric motor l5 whichis adapted to drive, through conventional type gearing IS, a crank 3Claims. (Cl. 175-182) arm ll on which is mounted a weight l8. The

22 in opposite directions.

crank arm I! is mounted in suitable bearin s l8 and 20 for rotationabout a vertical axis.

The crank arm ll drives, through conventional gearing 2|, a second crankarm 22, journalled in suitable bearings 23 and 24 for vertical rotationwithin the casing l4 and having a weight 25 mounted thereon. It will benoted that the gearing 2| causes the crank arms I! and 22 to rotate inopposite directions, when the motor I5 is in operation.

One terminal ofthe motor I5 is connected to a conductor 26 in thesupporting cable 21, the upper end of which is connected in series witha conventional type switch 28 and a suitable source of electrical energy29, the other terminal of which is connected to ground at the point 30at the surface of the earth. The energizing circuit for the motor I5 iscompleted through the earth and the bore hole liquid II and to this endits other terminal is grounded to the body of the apparatus H at thepoint 3|. If any interference is encountered between the current and therecording circuits, it may be desirable to use a second conductor in thecable 21 instead of the ground return.

In operation, the switch 28 at the surface of the earth is closed andthe apparatus In is moved through the bore hole I2. This energizes themotor i'5, causing it to drive the crank arms l1 and The result of thisrotation of the weights I8 and 25, respectively, on the crank arms I!and 22, respectively, is to impart an extremely vigorous vibratingmotion to the apparatus ill in a plane perpendicular to the paper. Thisvigorous vibration produces periodic increases and decreases in thepressure of the 14, preferably on a radius perpendicular to a linepassing through the centers of the bearings l9 and 23. The electrode 32may be connected through a conductor 33 in the supporting cable 21 toone terminal of a conventional alternating current potential indicatinginstrument 34, prefaemass erably of the. recording type, the otherterminal of which may be connected to a ground point II at the surfaceof the earth.

A representative curve such as might be obtained by the recordingapparatus 84 is shown in Figure 2, from which it appears that thespontaneous potential curve is modulated in the vicinity of the porousformation It at the frequency of vibration of the apparatus ID in thebore hole. The normal spontaneous potential curve, such as might beobtained with the switch 2. open, is shown in dotted lines for purposesof comparison.

In the embodiment described above, other measuring circuits may beemployed for obtaining indications of electrofiltration potentials in abore hole. For example, in Figure 1, indications of electroflltrationpotentials might be obtained by making measurements between theelectrode 32 and another electrode 80 located at the same level on theother side of the casing ll opposite the electrode 82 and connected bya.conductor II to the recorder 34, as in Fig. 3. This modificationproduces a curve of alternating electrofiltration potentials alone (Fig.4). As a further modification, indications might be obtained of thevoltages between each of two such electrodes and ground. 1

The invention thus provides a new apparatus for obtaining indications ofelectrofiltration potentials apart from other continuous potentials thatmay be present in a bore hole. By producing a localized and periodicallyvariable pressure variation at different depths in the bore hole,continuous electrofiltration potentials may be changed to alternatingpotentials that can be readily separated from other continuouspotentials which may be encountered. Accordingly, the invention enablesaccurate indications of electroflltration potentials to be obtainedwith-- out taking any special precautions even in wells located in thevicinity of relatively strong telluric currents.

The embodiment described above is intended to be illustrative and notrestrictive. Numerous modifications in form and detail may be made inthat embodiment within the scope of the following claims.

I claim:

1. In bore hole investigating apparatus, the combination of a bodyadapted to be lowered into a bore hole containing a liquid, an eccentricmass rotatably mounted in the body, power means for rotating said massto produce periodic pressure fluctuations in said liquid at a relativelyrapid rate above that to which a direct current meter is responsive,thereby generating variable altemating electroflltratlon potentials inthe vicinity of permeable formations, a first electrode assembled tosaid body so as to be movable at substantially the same level therewith,a second electrode located at a position where it is not subject to thesame instantaneous pressure as said first electrode, circuit meanstransmitting to the surface alternating potentials picked up by saidelectrodes and produced by said generated alternating electroflltrationpotentials, and means for providing indications of said alternatingpotentials.

2. In bore hole investigating apparatus, the combination of a bodyadapted to be lowered into a bore hole containing a liquid, a pair ofeccentric masses rotatably mounted in the body, electrical power meansfor rotating said masses to produce periodic pressure fluctuations insaid liquid at a relatively rapid rate above that to which a directcurrent meter is responsive, thereby generating variable alternatingelectroflltration potentials in the vicinity of permeable formations, asource of electrical energy at the surface, electrical means forenergizing said electrical power means from said source, a firstelectrode assembled to said body so as to be movable at substantiallythe same level therewith, a. second electrode located at a positionwhere it is not subject to the same instantaneous pressure as said firstelectrode, circuit means transmitting to the surface alternatingpotentials picked up by said electrodes and produced by said generatedalternating electrofiltration potentials, and means for providingindications of said alternating potentials.

3. In bore hole investigating apparatus, the combination of a bodyadapted to be lowered into a bore hole containing a liquid, an eccentricmass rotatably mounted in the body, power means for rotating said massto produce periodic pressure fluctuations in said liquid at a relativelyrapid rate above that to which a direct current meter is responsive,thereby generating variable alternating electroilltration potentials inthe vicinity of permeable formations, a first electrode assembled tosaid body so as to be movable at substantially the same level therewith,a second electrode located at substantially the same level as said firstelectrode and on the opposite side of the body therefrom, said first andsecond electrodes being so positioned that they are not subjected to thesame instantaneous fluid pressure, circuit means transmitting to thesurface alternatin potentials picked up by said electrodes and producedby said generated alternating electrofiltration potentials, and meansfor providing indications of said alternating potentials. I

HENRI-GEORGES DOLL.

No references cited.

